Simple_Q_Example.js

var Q = require('q');
var FS = require('fs');

var test = function(){
    var deferred = Q.defer();
    FS.readFile("foo.txt", "utf-8", function (error, text) {
        if (error) {
            deferred.reject(25);
        } else {
            deferred.resolve(text);
        }
    });
    return deferred.promise;
}

test()
    .then(function(){
        console.log("Success");
    })
    .fail(function(errorCode){
        console.log("Fail");
        console.log(errorCode);
        if (errorCode === 25) {
            console.log("We are good");
        }
    });